Method of making a multicomponent film

ABSTRACT

Described herein is a method and liquid-based precursor composition for depositing a multicomponent film. In one embodiment, the method and compositions described herein are used to deposit Germanium Tellurium (GeTe), Antimony Tellurium (SbTe), Antimony Germanium (SbGe), Germanium Antimony Tellurium (GST), Indium Antimony Tellurium (IST), Silver Indium Antimony Tellurium (AIST), Cadmium Telluride (CdTe), Cadmium Selenide (CdSe), Zinc Telluride (ZnTe), Zinc Selenide (ZnSe), Copper indium gallium selenide (CIGS) films or other tellurium and selenium based metal compounds for phase change memory and photovoltaic devices.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application claims the benefit of prior U.S. ProvisionalPatent Application Ser. No. 61/307,222 filed Feb. 23, 2010.

BACKGROUND OF THE INVENTION

Disclosed herein is a method for depositing multicomponent films each ofwhich may be stoichiometric or non-stoichiometric such as, but notlimited to, Germanium Tellurium (GeTe), Antimony Tellurium (SbTe),Antimony Germanium (SbGe), Germanium Antimony Tellurium (GST), IndiumAntimony Tellurium (IST), Silver Indium Antimony Tellurium (AIST),Cadmium Telluride (CdTe), Cadmium Selenide (CdSe), Zinc Telluride(ZnTe), Zinc Selenide (ZnSe), Copper indium gallium selenide (CIGS). Themethod described herein may, in certain embodiments, be used to depositthe multicomponent films as an alternative to existing vapor phasedeposition methods such as physical vapor deposition (PVD), chemicalvapor deposition (CVD) or atomic layer deposition (ALD). Liquid-basedprecursor compositions or mixtures thereof for depositing themulticomponent film using the method described herein are alsocontemplated.

Certain alloys such Cadmium Telluride, Cadmium Selenide, and Copperindium gallium selenide (CIGS) are of industrial interest because theycan be used as photovoltaic materials. Still other alloys including, butnot limited to, GST (Germanium Antimony Tellurium alloy), IST (IndiumAntimony Tellurium), and AIST (Silver Indium Antimony Tellurium), areused to fabricate electronic devices, including Phase Change RandomAccess Memory (PCRAM). Phase-change materials exist in a crystallinestate or an amorphous state according to temperature. A phase-changematerial has a more ordered atomic arrangement and a lower electricalresistance in a crystalline state than in an amorphous state. Aphase-change material can be reversibly transformed from the crystallinestate to the amorphous state based on an operating temperature. Suchcharacteristics, that is, reversible phase change and differentresistances of different states, are applied to newly proposedelectronic devices, a new type of nonvolatile memory devices,phase-change random access memory (PCRAM) devices. The electricalresistance of a PCRAM may vary based on a state (e.g., crystalline,amorphous, etc.) of a phase-change material included therein.

Among various types of phase-change materials used for memory devices,the most commonly used are ternary chalcogenides of Group 14 and Group15 elements, such as Germanium Antimony Tellurium compounds of variouscompositions, including but not limited to Ge₂Sb₂Te₅, commonlyabbreviated as GST. The solid phases of GST can rapidly change fromcrystalline state to amorphous state or vise versa upon heating andcooling cycles. The amorphous GST has relatively higher electricalresistance while the crystalline GST has relatively lower electricalresistance.

One of the technical hurdles in designing a PCRAM cell is that in orderto overcome the heat dissipation during the switching of GST materialsfrom crystalline to amorphous states a high level of reset current hasto be applied. This heat dissipation, however, can be greatly reduced byconfining GST material into contact plugs, thus reducing the resetcurrent needed for the action. The GST contact plugs are of high aspectratio structure, and conventional sputtering process for GST filmdeposition can not achieve high conformality required. This drives theneed for precursors and related manufacturing methods or processes forforming GST films which can produce films with high conformality andchemical composition uniformity.

BRIEF SUMMARY OF THE INVENTION

The method described herein provides an alternative to existing PVD, CVDor ALD depositions for depositing multicomponent films. Liquid-basedprecursor compositions or solutions comprising one or more precursorsfor depositing the multicomponent film using the method described hereinare also contemplated. Compared to the existing technologies, the methoddescribed herein may achieve at least one of the following objectives:are environmentally friendly, consume less precursor material, providecoverage for high aspect ratio features, and/or require less energy forproducing the film. The foregoing advantages may result in lower costsin depositing the film. It is believed that films deposited by themethod described herein can be used, for example, in the followingapplications: in semiconductor memory, solar cell technology, infraredsensors and/or devices.

One embodiment of the method for depositing a multicomponent film ontoat least a portion of a substrate comprises the steps of:

-   -   (a) contacting the substrate with a Ge precursor or a precursor        solution comprising the Ge precursor to react with the substrate        to provide a first coating layer comprising Ge;    -   (b) rinsing at least a portion of the first coating layer with a        rinse solution comprising a solvent to remove any unreacted Ge        precursor;    -   (c) contacting the first coating layer comprising Ge with a Te        precursor or a precursor solution comprising the Te precursor,        wherein at least a portion of the Te precursor reacts with at        least a portion of the Ge comprised therein to provide a second        coating layer comprising Ge and Te;    -   (d) rinsing at least a portion of the second coating layer with        rinse solution comprising a solvent to remove any unreacted Te        precursor;    -   (e) contacting the second coating layer comprising Ge and Te        with a Sb precursor or a precursor solution comprising the Sb        precursor, wherein at least a portion of the Sb precursor reacts        with at least a portion of the Ge and Te comprised therein to        provide a third coating layer comprising Ge, Te, and Sb;    -   (f) rinsing at least a portion of the third coating layer with        rinse solution comprising a solvent to remove any unreacted Sb        precursor;    -   (g) contacting the third coating layer comprising Ge, Te, and Sb        with a Te precursor or a precursor solution comprising the Te        precursor, wherein at least a portion of the Te precursor reacts        with at least a portion of the Ge and Sb comprised therein to        provide a fourth coating layer comprising Ge, Te, and Sb; and    -   (h) rinsing at least a portion of the fourth coating layer with        rinse solution comprising a solvent to remove any unreacted Te        precursor.

In certain embodiments, steps (a) through (h) are repeated a number oftimes until a desired thickness of coating layers is reached to providethe multicomponent film. In this or other embodiment, the steps may beperformed in the order of:e→f→g→h→a→b→c→d.

In a further embodiment, there is provided a process of depositing amulticomponent film onto at least a portion of a substrate comprisingthe steps of:

-   -   (a) contacting the substrate with an In precursor or a precursor        solution comprising the In precursor to react with the substrate        to provide a first coating layer comprising In;    -   (b) rinsing at least a portion of the first coated layer with a        rinse solution to remove any unreacted In precursor;    -   (c) contacting the first coating layer comprising In with a Te        precursor or a precursor solution comprising the Te precursor,        wherein at least a portion of the Te precursor reacts with the        In comprised therein to provide a second coating layer        comprising In and Te;    -   (d) rinsing at least a portion of the second coating layer with        rinse solution to remove any unreacted Te precursor;    -   (e) contacting the second coating layer comprising In and Te        with a Sb precursor or a precursor solution comprising the Sb        precursor, wherein at least a portion of the Sb precursor reacts        with at least a portion of the In and Te comprised therein to        provide a third coating layer comprising In, Sb, and Te;    -   (f) rinsing at least a portion of the third coating layer with        rinse solution to remove any unreacted Sb precursor,    -   (g) contacting the third coating layer comprising In, Te, and Sb        with a Te precursor or a precursor solution comprising the Te        precursor to provide a fourth coating layer comprising In, Te,        and Sb; and    -   (h) rinsing at least a portion of the fourth coating layer with        rinse solution to remove any unreacted Te precursor,    -   (i) contacting the fourth coating layer comprising In, Te, and        Sb with a Ag precursor or a precursor solution comprising the Ag        precursor, wherein at least a portion of the Ag precursor reacts        with at least a portion of the In, Te, and Sb comprised therein        to provide a fifth coating layer comprising In, Te, Sb and Ag;    -   (j) rinsing at least a portion of the fifth coating layer with        rinse solution to remove any unreacted Ag precursor;    -   (k) contacting the fifth coating layer comprising In, Te, Sb and        Ag with a Te precursor or a precursor solution comprising the Te        precursor to react with the fifth coating layer to provide a        sixth coating layer comprising In, Te, Sb and Ag; and    -   (l) rinsing at least a portion of the sixth coating layer with        rinse solution to remove any unreacted Te precursor,        wherein steps (a) through (l) are repeated to form a number of        coating layers to provide the film.

In yet another embodiment, there is provided a method of depositing amulticomponent film on a substrate comprising steps of:

-   -   (a) contacting the substrate with an In precursor or a precursor        solution comprising the In precursor to react with the substrate        to provide a first coating layer comprising In;    -   (b) rinsing at least a portion of the first coated layer with a        rinse solution to remove any unreacted In precursor;    -   (c) contacting the first coating layer comprising In with a Te        precursor or a precursor solution comprising the Te precursor,        wherein at least a portion of the Te precursor reacts with the        In comprised therein to provide a second coating layer        comprising In and Te;    -   (d) rinsing at least a portion of the second coating layer with        rinse solution to remove any unreacted Te precursor;    -   (e) contacting the second coating layer comprising In and Te        with a Sb precursor or a precursor solution comprising the Sb        precursor, wherein at least a portion of the Sb precursor reacts        with at least a portion of the In and Te comprised therein to        provide a third coating layer comprising In, Sb, and Te;    -   (f) rinsing at least a portion of the third coating layer with        rinse solution to remove any unreacted Sb precursor,    -   (g) contacting the third coating layer comprising In, Te, and Sb        with a Te precursor or a precursor solution comprising the Te        precursor to react with the third layer to provide a fourth        coating layer comprising In, Te, and Sb; and    -   (h) rinsing at least a portion of the fourth coating layer with        rinse solution to remove any unreacted Te precursor,        wherein steps (a) through (h) are repeated to form a number of        coating layers to provide the film.

In a still further embodiment, there is provided a method for depositinga film on at least a portion of a substrate comprising the steps of:

-   -   (a) contacting the substrate with a Cd precursor or a precursor        solution comprising the Cd precursor to react with the substrate        to provide a first coating layer comprising Cd;    -   (b) rinsing at least a portion of the first coating layer with a        rinse solution comprising a solvent or mixed solvent to remove        any unreacted Cd precursor;    -   (c) contacting the first coating layer comprising Cd with a Te        precursor or a precursor solution comprising the Te precursor,        wherein at least a portion of the Te precursor reacts with at        least a portion of the Cd comprised therein to provide a second        coating layer comprising Cd and Te;    -   (d) rinsing at least a portion of the second coating layer with        rinse solution comprising a solvent to remove any unreacted Te        precursor,        wherein steps (a) through (d) are repeated to form a number of        coating layers to provide the film.

In yet a further embodiment, there is provided a method of depositing amulticomponent film on at least a portion of a substrate comprising thesteps of:

-   -   (a) contacting the substrate with a Sb precursor or a precursor        solution comprising the Sb precursor to react with the substrate        to provide a first coating layer comprising Sb;    -   (b) rinsing at least a portion of the first coated layer with a        rinse solution to remove any unreacted Sb precursor;    -   (c) contacting the first coating layer comprising Sb with a Te        precursor or a precursor solution comprising the Te precursor,        wherein at least a portion of the Te precursor reacts with the        Sb comprised therein to provide a second coating layer        comprising Sb and Te;    -   (d) rinsing at least a portion of the second coating layer with        rinse solution to remove any unreacted Te precursor;    -   (e) contacting the second coating layer comprising Sb and Te        with a Ge precursor or a precursor solution comprising the Ge        precursor, wherein at least a portion of the Ge precursor reacts        with at least a portion of the Sb and Te comprised therein to        provide a third coating layer comprising Ge, Te, and Sb;    -   (f) rinsing at least a portion of the third coating layer with        rinse solution to remove any unreacted Ge precursor;    -   (g) contacting the third coating layer comprising Sb, Te, and Ge        with a Te precursor or a precursor solution comprising the Te        precursor to react with the third coating layer to provide a        fourth coating layer comprising Sb, Te, and Ge; and    -   (h) rinsing at least a portion of the fourth coating layer with        rinse solution to remove any unreacted Te precursor,        wherein steps (a) through (h) are repeated to form a number of        coating layers and provide the film.

In a further embodiment, there is provided a method of depositing amulticomponent film onto at least a portion of a substrate comprisingthe steps of:

-   -   (a) contacting the substrate with an Ge precursor or a precursor        solution comprising the Ge precursor to react with the substrate        to provide a first coating layer comprising Ge;    -   (b) rinsing at least a portion of the first coated layer with a        rinse solution to remove any unreacted Ge precursor;    -   (c) contacting the first coating layer comprising Ge with a Sb        precursor or a precursor solution comprising the Sb precursor,        wherein at least a portion of the Sb precursor reacts with at        least a portion of the Sb comprised therein to provide a second        coating layer comprising Ge and Sb;    -   (d) rinsing at least a portion of the second coating layer with        rinse solution to remove any unreacted Sb precursor,        wherein steps (a) through (d) are repeated to form a number of        coating layers to provide the film.

In yet another embodiment the present invention is a method ofdepositing a multicomponent film onto at least a portion of a substratecomprising steps of:

-   -   (a) contacting the substrate with a MX_(n) wherein M is a metal        or metalloid selected from the group consisting of: Ge, Sb, In,        Sn, Ga, Bi, Ag, Cu, Zr, Hf, Hg, Cd, Zn, Ru, Rh, Pd, Os, Ir, Pt        and Au; and X is neucleophilic group selected from the group        consisting of: OR (alkoxy), F (fluorine), Cl (chlorine), Br        (bromine), NR₂ (amino), CN (cyano), OCN (cyanate), SCN        (thiocyanate), diketonate, and carboxylic groups;    -   (b) rinsing at least a portion of the first coated layer with a        rinse solution to remove any unreacted precursor;    -   (c) contacting the first coating layer comprising an organosilyl        precursor or a precursor solution;    -   (d) rinsing at least a portion of the second coating layer with        rinse solution to remove any unreacted precursor,        wherein steps (a) through (d) are repeated to form a number of        coating layers to provide the film and the metal or metalloid        can be selected independently from step to step.

In the any of the preceding embodiments, it is understood that the stepsof the methods described herein may be performed in a variety of orders,may be performed sequentially or concurrently (e.g., during at least aportion of another step), and any combination thereof. In certainembodiments, the steps described herein are performed sequentially toavoid formation of precipitation.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 provides a cross-sectional view obtained by Scanning ElectronMicroscopy (SEM) of a GST film deposited using the liquid-baseddeposition method described herein on a Si (100) substrate.

FIG. 2( a). X-ray Photoelectron Spectroscopy (XPS) of GST-Ge Peak of theGST film from FIG. 1.

FIG. 2( b). XPS of GST-Sb Peak of the GST film from FIG. 1.

FIG. 2( c). XPS of GST-Te Peak of the GST film from FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

To fabricate high density electronic devices such as phase change memory(PCRAM) or photovoltaic materials, Atomic Layer Deposition (ALD) is apreferred technology to deposit films, such as metal chalcogenide films,uniformly on small dimensional structures on a substrate surface. Incertain embodiments, the film comprises a metal chalcogenide film. Theterm “metal chalcogenide” as used herein refers to a film that containsone or more Group 16 ion (chalcogenide) and at least one electropositiveelement. Examples of chalcogenide materials include, but are not limitedto, sulfides, selenides, and tellurides. Conventional ALD technologyinvolves ALD reactors which typically operate under vacuum and atelevated temperature. It also requires that the precursors be volatileand thermally stable compounds in order to be delivered to the reactorchamber in the vapor phase. ALD is a type of chemical vapor depositionthat is used for highly controlled deposition of thin films. It is aself-limiting (the amount of film material deposited in each reactioncycle is constant), sequential process (the precursor vapors are broughtonto the substrates alternately, one at a time, separated by purgingperiods with inert gas). ALD is considered as one deposition method withthe greatest potential for producing very thin, conformal films withcontrol of the thickness and composition of the films possible at theatomic level. Using ALD, film thickness depends only on the number ofreaction cycles, which makes the thickness control accurate and simple.

By contrast, the method described herein is a liquid-phase layerdeposition wherein each exposure of the substrate to a liquid precursorcomposition results in formation of about one atomic layer. Theprecursor used to form the coating layer is liquid-based, is in itsliquid phase or in a solution with one or more solvents that isliquid-based, and has one or more attributes of a liquid such as but notlimited to viscosity, flowability, wetting, compressability and thelike. The method described herein provides an alternative toconventional ALD technology by depositing the multicomponent films inALD manner in the liquid phase to generate high purity films at lowtemperature such as, for example, at ambient temperature. In the methoddescribed herein, the growth of the film is restricted by the chemistryof the precursor liquid in a self limiting surface reaction. Eachdeposition of the liquid-based precursor or a solution thereof onto thesurface may yield about one atomic layer which may be described hereinas a coating layer.

In certain embodiments, the method described herein uses one or moreprecursors that comprise a nucleophilic reagent. In this or otherembodiments, organosilyl compounds of Sb, Te and Se will react withnucleophilic reagents to form elemental Sb, Te or Se respectively by theelimination reaction between the organosilyl and nucleophilic groups,and subsequent decomposition of the hydrido compounds of Sb, Te or Se soformed. The nucleophilic reagent may comprise, but is not limited to,water, alcohols, hydrogen halide, or combinations thereof. Examples ofthis embodiment is illustrated in the following Equations (1) and (2):

In the above equations 1 and 2, R may be, but is not limited to, amethyl (“Me”) group, an ethyl (“Et”) group, a vinyl (“Vi”) group, aphenyl (“Ph”) group, or a H atom.

In other embodiments, the nucleophilic reagent may comprise a metal atombonded to the nucleophilic group. Ligand exchange reactions of Sb, Teand Se organosilyl precursors with a series of metal precursors havingnucleophilic substituents can be used to form metal alloys. In oneparticular embodiment, ligand exchange reactions of silyl-chalcogens,such as organosilyltellurium or silyltellurium, organosilylselenium orsilylselenium with a series of metal compounds having neucleophilicsubstituents generate metal chalcogenides. Because of this, binary,ternary, and multi-element metal tellurides and selenides containingfilms can be prepared using these methods. An example of this embodimentis illustrated in the following Equations (3) and (4);3 R₃Si—Te—SiR₃+2 SbX₃→Sb₂Te₃+3 R₃Si—X   (Equation 3)2 R₃Si—Te—SiR₃+GeX₄→Ge₂Te+4 R₃Si—X   (Equation 4)In the above equations 3 and 4, R may be, but is not limited to, amethyl (“Me”) group, an ethyl (“Et”) group, a vinyl (“Vi”) group, aphenyl (“Ph”) group, or a H atom; and X a nucleophilic group which maybe, but is not limited to, an alkoxide, an amide, a halide.

While not being bound to theory, the method described herein is based onthe discovery that exposing a substrate such as a silicon wafer tosequential treatments with one or more precursor liquids, solutions orsuspensions (referred to herein as “liquid precursor” or “precursorsolution”) results in the deposition of good quality films suitable foruse in manufacturing. The sequential treatment with liquid precursorsmay be considered a novel extension of the vapor phase technique knownas Atomic Layer Deposition but, whereas ALD is performed in vapor phase,the method described herein is performed in liquid phase.

In one embodiment, the method described herein may comprise a pluralityof liquid precursors which are designated as the 1^(st) or the 2^(nd)liquid precursor which are independently deposited onto the substratesurface in the following sequence:→1^(st) liquid precursor→2^(nd) liquid precursor→(repeat)This above sequence or cycle may be repeated multiple times in order tobuild up a film of desired thickness consisting of a plurality ofcoating layers. Individual cycles are self limiting—exposure to a liquidprecursor causes absorption of the precursor onto the surface up to asaturation level which cannot be exceeded, and exposure to the 2^(nd)liquid fully converts the absorbed layer. The sequence is therefore aself limiting surface reaction and confers the benefits of perfectconformality and precise thickness control.

In this or other embodiments, the method described herein may bemodified by adding rinse steps between exposures to the one or moreprecursor liquids in order to remove excess precursor from the substratesurface and thereby ensure that a self limited surface reaction occurs.An example of this embodiment is shown as follows:→1^(st) liquid precursor→rinse→2^(nd) liquid precursor→rinse→(repeat)In this embodiment or in a further embodiment, the above sequence orcycle may further be modified by adding an additional precursor liquidexposure step or exposure to 3^(rd) liquid precursor in order to deposita ternary or higher order film. An example of this embodiment is shownas follows:→1^(st) liquid precursor→rinse→2^(nd) liquid precursor→rinse→3^(rd)liquid precursor→rinse→(repeat)

In one particular embodiment for depositing a GST film, the GST film maybe deposited using the following sequence:→Ge liquid precursor→rinse→Te liquid precursor→rinse→Sb liquidprecursor→rinse→Te liquid precursor→rinse→(repeat)In this sequence, the substrate surface is first saturated with the Geprecursor to react with the substrate surface to provide a first coatinglayer, and any excess Ge precursor is removed in the rinse. Next, the Teprecursor is allowed to react with the Ge on the surface to provide asecond coating layer and any excess Te precursor is rinsed off to leavea saturated surface concentration of Te. Then, the Sb precursor isintroduced and reacts with the surface Te to form a saturated coveringof Sb or a third coating layer, which is then rinsed to remove anyexcess Sb precursor. The substrate is then subjected to an additionaltreatment with the Te precursor, which reacts with the Sb-saturatedsurface to provide a Te covering or additional coating layer, which isrinsed to remove any excess Te precursor. As with the previousembodiments, the entire sequence or cycle can be repeated multiple timesthereby forming multiple coating layers to achieve the desired filmthickness. It is understood that the method described herein can includeany number of orders of introducing the Te, Sb, and Ge precursors and isnot limited thereto.

In certain embodiments, alloys incorporating a combination of more thanone of the elements Sb, Te and Se may be formed by using more than onesequence based on the method described herein. For example, an alloycontaining both Sb and Te could be formed by using organosilyl compoundsof both Sb and Te along with a nucleophilic reagent as previouslydefined. However, in other embodiments it is not necessary that eitherone or both Sb and Te precursors comprise organosilyl substituents. Inone particular embodiment, the Te precursor comprises anorganosilyltellurium compound and the Sb precursor comprises a compoundin which the Sb atom is already attached to a nucleophilic substituent.

The method described herein may also use—in certainembodiments—silylchalcogens, such as silyltellurium and silylseleniumcompounds as precursors for tellurium and selenium sources, which reactwith metal compounds having nucleophilic substituents to form metaltellurides and metal selenides. Ternary and quaternary telluride andselenide films can be made by adding one or more additional precursors,or precursor solutions comprising same, in a sequential manner or in amixed manner, in a process similar to an ALD process. The material andthe technologies disclosed herein can be used for the deposition of GSTfilms or other metal chalcogenide films for phase change memoryapplications, and various thin films in photovoltaic devices.

Examples of tellurium precursors or Te precursors may comprisedisilyltellurium, silylalkyltellurium, or compounds having the generalstructures of: (R¹R²R³Si)₂Te and (R¹R²R³Si)R⁴Te. Examples of Selenium orSe precursors may comprise disilylselenium, silylalkylselenium, orcompounds having the general structures of: (R¹R²R³Si)₂Se or(R¹R²R³Si)R⁴Se. In the foregoing formulas, substituents R¹, R², R³, andR⁴ are each independently: hydrogen; linear, branched, or unsaturatedC₁₋₁₀ alkyl groups; and C₄₋₁₀ cyclic alkyl groups, or C₄₋₁₂ aromaticgroups. The term “alkyl” as used herein is selected from the groupconsisting of: linear, branched, or unsaturated C₁₋₁₀ alkyl groups; andC₄₋₁₀ cyclic alkyl groups, preferably from 1 to 6 carbon atoms, morepreferably from 1 to 3 carbon atoms, alternately from 3 to 5 carbonatoms, further alternately from 4 to 6 carbons atoms, or variations ofthe foregoing ranges. Exemplary alkyl groups include, but are notlimited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,sec-butyl, tert-butyl, tert-amyl, n-pentyl, n-hexyl, cyclopentyl, andcyclohexyl. The term “alkyl” applies also to alkyl moieties contained inother groups such as haloalkyl, alkylaryl, or arylalkyl. In certainembodiments, some of the groups discussed herein may be substituted withone or more other elements such as, for example, a halogen atom or otherheteroatoms such as O, N, Si, or S.

Examples for the silyltellurium precursor include, but are not limitedto, bis(trimethylsilyl)tellurium, bis(dimethylsilyl)tellurium,bis(triethylsilyl)tellurium, bis(diethylsilyl)tellurium,bis(phenyldimethylsilyl)tellurium, bis(t-butyldimethylsilyl)tellurium,dimethylsilylmethyltellurium, dimethylsilylphenyltellurium,dimethylsilyl-n-butyltellurium, dimethylsilyl-t-butyltellurium,trimethylsilylmethyltellurium, trimethylsilylphenyltellurium,trimethylsilyl-n-butyltellurium, and trimethylsilyl-t-butyltellurium.

The deposited films are selected from the group selected from GermaniumTellurium (GeTe), Antimony Tellurium (SbTe), Antimony Germanium (SbGe),Germanium Antimony Tellurium (GST), Indium Antimony Tellurium (IST),Silver Indium Antimony Tellurium (AIST), Cadmium Telluride (CdTe),Cadmium Selenide (CdSe), Zinc Telluride (ZnTe), Zinc Selenide (ZnSe),Copper indium gallium selenide (GIGS).

In certain embodiments, the method described herein or the liquidprecursor comprises one or more metal compounds have the general formulaof:MX_(n)where M is the metal selected from the periodic table of elements,including but not limited to: Ge, Sb, In, Sn, Ga, Bi, Ag, Cu, Zr, Hf,Hg, Cd, Zn and noble metals; and X is neucleophilic group such as OR(alkoxy), F (fluorine), Cl (chlorine), Br (bromine), NR₂ (amino), CN(cyano), OCN (cyanate), SCN (thiocyanate), diketonate, or carboxylicgroups. In certain embodiments, the M comprises In and is used todeposit an AIST film. In this or other embodiment, the M comprises Agand is also used to deposit an AIST film.

In certain embodiments wherein the liquid precursor comprises a Geprecursor, examples of Ge compounds include but are not limited to:

-   -   (R¹O)₄Ge or (R¹O)_(n)GeX_(4-n) where R¹ is an alkyl group with 1        to 10 carbon chain, branched, cyclic, or aromatic group; and n=1        to 3; X is H, or nucleophilic groups such as F (fluorine), Cl        (chlorine), Br (bromine), NR₂ (amino), CN (cyano), OCN        (cyanate), SCN (thiocyanate), diketonate, or carboxylic groups,        or a combination thereof.    -   (R⁵R⁶N)₄Ge or (R⁵R⁶N)_(4-n)GeX_(n), where R⁵ and R⁶ are each        independently alkyl groups with 1 to 10 carbons in chain,        branched, cyclic, or aromatic group; and n=1 to 3; X is H, or        nucleophilic groups such as OR (alkoxy), F (fluorine), Cl        (chlorine), Br (bromine), CN (cyano), OCN (cyanate), SCN        (thiocyanate), diketonate, or carboxylic groups or a combination        thereof, and    -   GeX₄, GeX₂, or R_(n)GeX_(4-n), where X is nucleophilic groups        such as OR (alkoxy), F (fluorine), Cl (chlorine), Br (bromine),        NR₂ (amino), CN (cyano), OCN (cyanate), SCN (thiocyanate),        diketonate, or carboxylic groups or a combination thereof, R is        hydrogen; linear, branched, or unsaturated C₁₋₁₀ alkyl groups;        and C₄₋₁₀ cyclic alkyl groups or C₄₋₁₂ aromatic groups; and        n=0-3.

In certain embodiments wherein the liquid precursor comprises a Sbprecursor, examples of Sb compounds include, but are not limited to:

-   -   (R⁷O)₃Sb, where R⁷ is linear, branched, or unsaturated C₁₋₁₀        alkyl groups; or C₄₋₁₀ cyclic alkyl groups;    -   (R⁷R⁸N)₃Sb, where R⁷ and R⁸ are individually linear, branched,        or unsaturated C₁₋₁₀ alkyl groups; and C₄₋₁₀ cyclic alkyl        groups; and    -   antimony halides with the general formula: SbX₃ and SbX₅, where        X is F, Cl, or Br.

While not being bound by theory, it is believed that silicon-telluriumbonds and silicon-selenium bonds are highly reactive toward nucleophilicattack due to their high degree of ionic character and low bond energy.When these compounds react, for example, with the metal compound MX_(n),the silyl groups may combine with the electronegative ligands X to formstronger bonds which results in the formation of metal-tellurium bondsand metal-selenium bonds. Studies shows the chemical bond reactivity onthe silicon atom has the following order. The bond with high reactivitycan be readily converted to the one with low reactivity. The chemicalbond reactivity from high activity to low activity is shown below:Si—Te>Si—I>Si—Se>Si—S>Si—Br>Si—Cl>Si—CN>Si—NCS>Si—O>Si—F

The formation of a metal telluride film using the method describedherein can be demonstrated by the following exemplary reactions amongstprecursor compounds:Me₃Si—Te—SiMe₃+M(OR)_(n)→MTe+Me₃SiORMe₃Si—Te—SiMe₃+M(F)_(n)→MTe+Me₃SiFMe₃Si—Te—SiMe₃+M(NR₂)_(n)→MTe+Me₃SiNR₂

The formation of a metal selenide film using the method described hereincan be demonstrated by the following exemplary reactions amongstprecursor compounds:Me₃Si—Se—SiMe₃+M(OR)_(n)→MSe+Me₃SiORMe₃Si—Se—SiMe₃+M(F)_(n)→MSe+Me₃SiFMe₃Si—Se—SiMe₃+M(NR₂)_(n)→MSe+Me₃SiNR₂

The formation of a GST using the method described herein can bedemonstrated by the following exemplary reactions amongst precursorcompounds:Me₃Si—Te—SiMe₃+Ge(OMe)₄+Sb(OEt)₃→GeSbTe+Me₃SiOEt+Me₃SiOMeMe₃Si—Te—SiMe₃+GeF₄+SbF₅→GeSbTe+Me₃SiFMe₃Si—Te—SiMe₃+Ge(NMe₂)₄+Sb(NMe₂)₃→GeSbTe+Me₃SiNMe₂In the above reactions, GeSbTe represents a general formula of GermaniumAntimony Telluride compounds, wherein the ratio of three elements maydiffer depending upon the end use.

The sequential liquid based deposition method for depositing GeSbTefilms on a substrate from silyltellurium compound, alkoxygermane andalkoxyantimony can be illustrated by the reaction scheme shown below.

In the reaction scheme shown above, rinse steps are not shown becausethey are used to remove the excess precursor solution from the coatinglayer. It is believed that the rinse step may avoid excess reaction,such as by the preceding precursor solution and the newly introducedprecursor solution, which may generate particles or precipitates on thesurface of the coating layer. A similar reaction sequence as thatprovided above may be adopted for the those embodiments wherein a GeSbSe(Germanium Antimony Selenium) film is deposited using liquid precursorssuch as silylselenium compound, alkoxygermane, and alkoxyantimony.

In one particular embodiment, the method and/or precursor solution maybe used to deposit CdTe materials that are suitable for photovoltaicdevices. An example of one method of depositing CdTe materials is shownin the following reaction:Me₃Si—Te—SiMe₃+Cd(OMe)₂→CdTe+Me₃SiOMe

The precursors used herein may be employed as pure liquid compounds ifthey are liquids under ambient conditions In this or other embodiments,the precursors can be dissolved in a suitable solvent to provide asolution comprising the precursor. In these or other embodiments, thesolvent employed in the precursor solution may be any suitable solventin which the precursor may be dissolved or suspended and which does notimpede the deposition such as by causing unwanted side reactions. Incertain embodiments, the one or more solvents in the precursor solutionexclude oxygen because it may react with silytellurim compounds. Furtherattributes for solvents to be used herein include one or more of thefollowing: proper boiling point, surface tension, and viscosity toprepare uniform films across 300 mm wafers, gap-fill features, and allowthe mixture to adequately wet any passivation layers, such as CVDsilicon nitride or silicon oxide. Examples of suitable solvents whichmay be employed as precursor solvents and/or rinse solvents include, butare not limited to: aliphatic hydrocarbons (e.g., C₅-C₁₂ aliphatichydrocarbons such as hexane, heptane, octane, and/or pentane), aromatichydrocarbons (e.g., C₆-C₁₈ aromatic hydrocarbons such as benzene,toluene, and/or mesitylene), nitriles, ethers (e.g., dialkyl etherscomprising C₁-C₆ alkyl moieties or C₄-C₈ cyclic ethers), and mixturesthereof. Specific solvents which can be advantageously employed hereincomprise, but are not limited to, hexane, pentane, heptane, cyclohexane,octane, toluene, and combinations thereof. Further examples of solventsinclude chlorinated hydrocarbons, ethers, glycol ethers, and mixturesthereof.

In certain embodiments, the precursors used to deposit the metal filmsare precursor solutions comprising one or more of a particular precursorcompound and one or more solvents that provided that the one or moresolvents does not react with the precursor compound contained therein.In these or other embodiments, the rinse solvent may be the same solventas the precursor solution solvent. In other embodiments, the one or morerinse solvent differs from the one or more solvent used in the precursorsolution. In one particular embodiments, hydrocarbon solvents such as,for example, hexanes or octane and/or aromatic hydrocarbons such as, forexample, may be used as solvents within the liquid precursor solutionand/or as the rinse solvent.

In embodiments wherein the precursor is provided as a precursorcomposition or solution, the amount of solvent(s) present may range fromabout 0.01 to about 99.9 weight percent or from about 1 to about 50weight percent, preferably 1 to 10 weight percent.

The solvent employed in the precursor solution and/or the rinse solutionhas a relatively low boiling point in order for the residual solvent ifpresent to be readily removed. Exemplary boiling point temperatures forthe solvents disclosed herein include ranges having any one or more ofthe following endpoints: 200, 195, 190, 185, 180, 175, 170, 165, 160,155, 150, 145, 140, 135, 130, 125, 120, 115, 110, 105, 100, 95, 90, 85,80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, and/or 20° C. Examplesof particular melting point ranges include, but are not limited to, fromabout 20 to about 200° C. or from about 50 to about 100° C.

The precursor, precursor composition, precursor solution, and/or rinsesolution has a relatively low viscosity in order to permeate high aspectfeatures of a substrate. In one particular embodiment, the precursorcomposition or solution has a viscosity or 50 centipoise (cP) or less,or 45 cP or less, or 40 cP or less, of 35 cP or less, or 30 cP or less,or 25 cP or less, or 20 cP or less, or 15 cP or less, or a viscosity of10 cP or less when measured at 25° C.

The substrate may be contacted with the precursor or precursor solutionthrough a variety of methods which may comprise, but are not limited to,immersion in a bath of the liquid precursor, dip-coating, spin-oncoating, and spraying the liquid precursor onto the surface of thesubstrate. The actual conditions of the contacting step (i.e.,temperature, time, and the like) may vary over wide ranges and aregenerally dependent on a variety of factors such as, but not limited to,the nature and amount of residue on the surface of the substrate and thehydrophobicity or hydrophilicity of the substrate surface, etc. Thecontacting step can be conducted in either a dynamic method such as, forexample, a streamline process for applying the liquid precursor(s) overthe surface of the substrate or spin-coating; in a static method suchas, for example, a puddle rinse or immersing the substrate within a bathcontaining the liquid precursor(s); or a combination of static anddynamic methods (e.g., immersion in a liquid bath where the bath isagitated). The liquid precursor may also be sprayed onto the surface ofthe substrate in a dynamic method such as in a continuous process orsprayed onto the surface and allowed to remain there in a static method.The duration of the contacting step, or time of contact of the processsolution to the substrate surface, can vary from a fraction of a secondto hundreds of seconds. Preferably, the duration can range from 1 to 200seconds, preferably from 1 to 150 seconds, and more preferably from 1 to40 seconds. The temperature range for the contacting step can vary from10 to 100° C. and more preferably from 10 to 40° C.

In certain embodiments, the liquid precursor or precursor solutioncontacts the substrate using a spin-on deposition method. In oneparticular embodiment, approximately 2 milliliters of precursor orprecursor solution was dispensed through a 0.5 micron Teflon filterdirectly onto the wafer spinning at 500 rpm for 10 seconds under aninert atmosphere such as, but not limited to, N₂ or argon. Afterdispense was complete, the wafer was rinsed with a solvent such as forexample, the solvent comprising the precursor solution if present, andspun to remove excess solvent. This process is continued with one ormore additional precursor or precursor solutions to provide the metalfilm.

In the method and/or precursor composition comprised herein, the liquidprecursor or precursor solution may be provided simultaneously,sequentially, or in any combination thereof during the deposition.Alternatively, the precursors may also be provided sequentially byproviding a precursor and purging the unadsorbed precursor prior toproviding the next precursor on the coating layer surface. Thus, aprecursor that has been supplied but not adsorbed may be purged.

As mentioned previously, the method described herein may be used todeposit a metal-containing film onto at least a portion of a substrate.Examples of suitable substrates include but are not limited to, silicon,SiO₂, Si₃N₄, OSG, FSG, silicon carbide, hydrogenated silicon carbide,silicon nitride, hydrogenated silicon nitride, silicon carbonitride,hydrogenated silicon carbonitride, boronitride, antireflective coatings,photoresists, organic polymers, porous organic and inorganic materials,metals such as copper and aluminum, and conducting metal layers such asbut not limited to TiN, Ti(C)N, TaN, Ta(C)N, Ta, W, or WN. The films arecompatible with a variety of subsequent processing steps such as, forexample, chemical mechanical planarization (CMP) and anisotropic etchingprocesses. With the deposition chemistry described herein, highlyconformal films, such as but not limited to, GeSbTe or GeSbSe can bedeposited on the surface of substrate materials such as silicon, siliconoxide, silicon nitride, titanium nitride, and titanium oxide.

While the method and precursor compositions have been described indetail and with reference to specific examples and the embodimentsthereof, it will be apparent to one skilled in the art that variouschanges and modifications can be made therein without departing from thespirit and scope thereof.

EXAMPLES

GeTe, SbTe, GeSbTe (GST) films were deposited by the method describedherein. Scanning electron microscope (SEM) was used to obtaincross-sectional image and surface morphology of samples. The phasetransition properties of samples and films were characterized by EnergyDispersive X-ray Analysis.

Example 1 Deposition of GST Film

GST was deposited on Si(100) substrates previously coated with 100 nmTiN, because TiN is considered as an electrode or heater material forPCRAM devices. Eight baths were prepared respectively containing:

-   -   (1) 5% by weight of a precursor solution comprising Ge(OMe)₄ and        Hexane    -   (2) Hexane    -   (3) 5% by weight of a precursor solution comprising Te(SiMe₃)₂        and Hexane    -   (4) Hexane    -   (5) 5% by weight of a precursor solution comprising Sb(OEt)₃ and        Hexane    -   (6) Hexane    -   (7) 5% by weight a precursor solution comprising Te(SiMe₃)₂ and        Hexane    -   (8) Hexane

The substrate was dipped in each bath for 3 seconds before being movedon to the next one in turn, and the full cycle was repeated 100 times.The substrate was then dried and the presence of an approximately 100nanometer (nm) GST film was confirmed by SEM (FIG. 1) and XPS (FIG. 2(a)-(c)).

Example 2 Deposition of Cadmium Telluride (CdTe) Film

Cadmium telluride was deposited on Si(100) substrates. Eight baths wereprepared respectively containing:

-   -   1. 5% by weight of a precursor solution comprising Cd(OEt)₂ and        Hexane    -   2. Hexane    -   3. 5% by weight of a precursor solution comprising Te(SiMe₃)₂        and Hexane    -   4. Hexane        The substrate was dipped in each bath for 3 seconds before being        moved on to the next one in turn, and the full cycle was        repeated 100 times. The substrate was then dried.

The aforementioned examples are merely illustrative, and do not limitthis disclosure in any way. Other multi-component films including butnot limited to Indium Antimony Tellurium (IST), Silver Indium AntimonyTellurium (AIST), Cadmium Telluride (CdTe), Zinc Telluride (ZnTe), ZincSelenide (ZnSe), Cadium Selenide, Copper indium gallium selenide (CIGS)can be prepared in similar fashion.

1. A method of depositing a multicomponent film on at least a portion ofa substrate comprising steps of: (a) contacting the substrate with an Inprecursor or a precursor solution comprising the In precursor to reactwith the substrate to provide a first coating layer comprising In; (b)rinsing at least a portion of the first coated layer with a rinsesolution to remove any unreacted In precursor; (c) contacting the firstcoating layer comprising In with a Te precursor or a precursor solutioncomprising the Te precursor, wherein at least a portion of the Teprecursor reacts with the In comprised therein to provide a secondcoating layer comprising In and Te; (d) rinsing at least a portion ofthe second coating layer with rinse solution to remove any unreacted Teprecursor; (e) contacting the second coating layer comprising In and Tewith a Sb precursor or a precursor solution comprising the Sb precursor,wherein at least a portion of the Sb precursor reacts with at least aportion of the In and Te comprised therein to provide a third coatinglayer comprising In, Sb, and Te; (f) rinsing at least a portion of thethird coating layer with rinse solution to remove any unreacted Sbprecursor, (g) contacting the third coating layer comprising In, Te, andSb with a Te precursor or a precursor solution comprising the Teprecursor to react with the third coating layer to provide a fourthcoating layer comprising In, Te, and Sb; and (h) rinsing at least aportion of the fourth coating layer with rinse solution to remove anyunreacted Te precursor, (i) contacting the fourth coating layercomprising In, Te, and Sb with a Ag precursor or a precursor solutioncomprising the Ag precursor, wherein at least a portion of the Agprecursor reacts with at least a portion of the In, Te, and Sb comprisedtherein to provide a fifth coating layer comprising In, Te, Sb and Ag;(j) rinsing at least a portion of the fifth coating layer with rinsesolution to remove any unreacted Ag precursor; (k) contacting the fifthcoating layer comprising In, Te, Sb and Ag with a Te precursor or aprecursor solution comprising the Te precursor to react with the fifthcoating layer to provide a sixth coating layer comprising In, Te, Sb andAg; and (l) rinsing at least a portion of the sixth coating layer withrinse solution to remove any unreacted Te precursor, wherein steps (a)through (l) are repeated to form a number of coating layers to providethe film.
 2. The method of claim 1 wherein the Ag precursor comprises acompound having the following formula: MX_(n) wherein M is Ag; X is anucleophilic group selected from the group consisting of OR (alkoxy), F(fluorine), Cl (chlorine), Br (bromine), NR₂ (amino), CN (cyano), OCN(cyanate), SCN (thiocyanate), diketonate, carboxylic groups and mixturesthereof; and n=1 to
 3. 3. The method of claim 1 wherein the In precursorcomprises a compound having the following formula: MX_(n) wherein M isIn; X is a nucleophilic group selected from the group consisting of OR(alkoxy), F (fluorine), Cl (chlorine), Br (bromine), NR₂ (amino), CN(cyano), OCN (cyanate), SCN (thiocyanate), diketonate, carboxylic groupsand mixtures thereof; and n=1 to
 3. 4. The method of claim 1 wherein theTe precursor comprises a silyltellurium selected from the groupconsisting of disilyltellurium having a general formula: (R¹R²R³Si)₂Te;alkylsilyltellurium having a general formula: (R¹R²R³Si)TeR⁴; andmixtures thereof wherein R¹, R², R³, and R⁴ are each independentlyselected from the group consisting of: hydrogen; linear, branched, orunsaturated C₁₋₁₀ alkyl groups; C₄₋₁₀ cyclic alkyl groups; and C₄₋₁₂aromatic groups.
 5. The method of claim 1 wherein the Sb precursorcomprises a compound having the following formula: MX_(n) wherein M isSb; X is a nucleophilic group selected from the group consisting of OR(alkoxy), F (fluorine), Cl (chlorine), Br (bromine), NR₂ (amino), CN(cyano), OCN (cyanate), SCN (thiocyanate), diketonate, carboxylic groupsand mixtures thereof; and n=3 to
 5. 6. The method of claim 1 wherein theat least one of the Ag, the In, the Te, and the Sb precursors in thecontacting steps comprises a precursor solution.
 7. The method of claim6 wherein the precursor solution comprises the precursor and at leastone solvent selected the group consisting of a hydrocarbon, ahalogenated hydrocarbon, and an ether.
 8. The method of claim 7 whereinthe solvent comprises a hydrocarbon.
 9. The method of claim 8 whereinthe solvent is at least one selected from the group consisting ofhexane, octane, toluene, and combinations thereof.
 10. The method ofclaim 6 wherein the amount of solvent in the precursor solution rangesfrom about 0.01 to about 90 weight percent.